Idaho Code § 43-1325

Whenever the partitioned irrigation districts share irrigation works, canals and laterals after the partition takes effect, a joint board of control, not exceeding seven (7) members, shall be chosen by the board of directors of the respective partitioned irrigation districts, the members of which shall be apportioned to each district as nearly as practicable in accordance with the acreage for which water shall be provided in each respective district. Said board of control shall control, manage and operate such joint works subject to the board of directors of the respective districts and each member of the board of control shall hold office at the will of the board of directors of the district appointing such member.